Hi all,
I am a producer in Nor Cal Silicon Valley and am wondering if the multiple layering of drywall and green glue would have the cumulative effect I am looking for. I am researching soundproofing and will begin a construction phase soon. My idea is to use 7 layers of 5/8" drywall and 6 layers of green glue to build {attached to an existing layer of 1/2"} a "drywall wall" instead of using insulation to fill the cavities between studs. I am hoping to totally block sound from a 110 dB sound source from the other room that this wall is shared by. My studio dimensions are 17.5' long, 11.5' wide and 8.5' high. I know about double stud frame wall construction techniques, MLV, resilent channel systems, differing brands of insulation etc. I am trying to get the most bang for my buck here obviously, but am more concerned with getting 100% sound isolation for my own recording and mastering purposes. Either someone has tried this and has failed so miserably they would never dare admit their mistake and misfortune in public, or have been so successful in totally blocking massive SPL's that they have trademarked the idea and are profiteering it all the way around the world.
Care to enlighten me?
Cheers and Happy Trails,
RAD
Drywall as insulation.
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Soundman2020
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Re: Drywall as insulation.
Hi "RAD" Please read the forum rules for posting (click here). You seem to be missing a couple of things! 
There's a principle of physics (and acoustics) called "Mass Law", which basically says that every time you double the mass on a wall, you get an increase of 5 dB in isolation. So starting with a single sheet of drywall, that gets you about 25 dB of isolation. Double that (total of two layers), and you get about 30 dB. Double that again (total of four layers) you get 35 dB. Double that again (total of 8 layers) and you get 40 dB. That's already one layer more than you planned to use, and you are only at a measly 40 dB! Not very heartening.
Here's the actual equation for empirical mass law, if you are interested:
TL = 14.5 log (Ms * 0.205) + 23 dB
Where: Ms = Surface Mass in kg/m2
Secondly, has to do with two of your other comments:
So you cannot isolate 100%. It isn't possible. That's why we studio designers and acousticians don't like to use the word "soundproofing", because there's no such thing! We prefer "isolation".
But what you CAN do, is to isolate sounds down to a level where they are inaudible to the human ear. That, indeed, is achievable. For most people, if you place them in a location where the ambient sound level is 30 dBC, they will say that it is "silent". It isn't really silent, of course, since the level is 30 dB, which is 1000 times louder than the limit of human hearing, but most people consider that to be "silent" or at least "really, really, REALLY quiet".
So taking that as a reference, if you have a level of 110 dBC on one side of the wall, and you want subjective silence on the other side, then you need 110-30=80 dB of isolation.
80 dB of isolation is a tall, tall order. Very tall. Million dollar tall. It's beyond the capability of most home studios / project studios: It is achievable, but it is very high budget, and involves things like floated slabs and huge mass.
The practical isolation limit for most home studios is about 70 dB, as that's roughly the flanking limit for concrete slab on grade. That is do-able, but still hard. Most home studio builders are really happy to get 50 dB of isolation, and that's a reasonable goal to shoot for on a typical budget. 60 dB is also do-able, with good design and very careful construction.
So, with a 110 dB sound level on one side of the wall, 60 dB of isolation will get you about 50 dB on the other side of the wall. That is still audible, but certainly not loud at all.
There's also the spectrum to consider: If the sound you are isolating is strongest in the mid range, with not too much energy in the low end of the spectrum, then 60 dB of isolation will make it inaudible. For example, most power tools, vacuum cleaner, several people yelling and screaming at each other, etc. But if your 110 dB is a lone six-string bass guitar rehearsing all by itself at the level, it will be audible on the other side. Because isolation is not linear across the spectrum... isolating high frequencies is dead easy, mid range somewhat harder, and low frequencies, very hard.
I'm dead serious.
Above, I mentioned the concept of "mass law" above, since that's what you are talking about: making a single, solid wall that is purely mass. That's actually the worst type of wall you can have for isolation. Which is why studios NEVER use it.
The way to get good isolation (and the method used by all studios, including the 100 dB isolated Galaxy Studios) is with something called "fully decoupled two-leaf MSM isolation". This is also often called "room inside a room" construction. The basic concept is that you start with an empty piece of land, you pour a normal concrete slab on grade, then you build an outer "shell" building that has a decent amount of mass on it (but not hugely spectacular) concentrated in just one "leaf", then you build another structure inside that one, completely independent and self-supporting, such that it does not touch the outer building at all, and you also put one single leaf of mass on that.
For example: the outer building could be a stud frame with OSB and siding, plus an OSB roof deck with shingles, and all of that attached to the outside of the framing. So when you stand inside, you see studs and joists all around you, and the concrete floor. Then the inner-leaf building could also be a stud frame with drywall on only one side of it: just four walls and a ceiling, all framed and sheathed on just one side.
That's it! That's all you need.
The reason this works is because it is NOT subject to mass law! It is a resonant system, that is carefully tuned. Because it is resonant, it is subject to an entirely different set of equations that are only distantly related to mass law.
Resonance is a powerful tool. If you design the wall system correctly (tuned right), then you can get really good isolation like this, with not too much mass.
I could go into all the technical details of why this works, if you want, but suffice it to say that it does work, and it works very well. Much, much better than mass law. That's how I design all of my studios, and how pretty much all studio designers do it.
So you might think "Well, if one leaf is bad, and two leaves is good, then three leaves must be better!" And you'd be wrong...! 3-leaf, 4-leaf and multi-leaf systems actually turn out to have worse isolation in low frequencies, for complex technical reasons. The most efficient, most effective, lowest-cost method for isolating a studio, is fully-decouled, 2-leaf, MSM.
The truth is simple: the equations for isolation have no place for plugging in the price! They have a place where you can plug in the mass (weight) of the material, and MLV certainly has mass. But so do many other things, such as drywall, fiber-cement board, brick, concrete block, MDF, OSB, plywood, etc. If you compare the cost-per-pound (or cost per kg), you'll find that MLV is dam expensive! It is mass, yes, but it is darn costly mass! Ans since sound waves don't know how to read price tags, they really don't care how much you paid for your mass. They just see the actual physical mass, and that's what they react to. so it makes sense to get the cheapest mass available that will do the job. In most places around the world, that is usually plain old drywall.
I would suggest that you should take some time to study the acoustics and physics principles of sound isolation, and also to study the science/art of studio design, and the construction methods, techniques and common practices, so that you can correctly design your wall to be suitably tuned for the purpose.
It's not just wall design that you need to be concerned about: you can have a fantastic wall, ceiling and floor system that gets you amazing isolation, but then you have to put a door in it... doors are major weak points, since they have to open. You need to pay a lot of attention to your door design. Windows are weak point too, but the weakest point of all is usually the HVAC system. In order to stay alive in inside your studio, you need to breathe! (duh!). which implies that you need a constant supply of fresh air, and a way to exhaust the stale air. That implies shopping huge gaping holes in your perfect isolation, to pass the HVAC ducts through. There are ways of dealing with that, using specially designed "silencer boxes" that allow air to get through while stopping sound, but they have to be designed carefully too. In fact, the entire HVAC system has to be designed carefully, for many reasons: For example, moving air is noisy! The faster it moves, the noisier it is. So you have to design the entire system such that it moves enough air volume to keep you alive and comfortable while keeping the air flow speed down low enough that it does not make any noise that would interfere with your work or concentration. If you are mastering, you don't want a constant background "hiss" or "roar" coming from the HVAC vents!
Don't rush!
- Stuart -
No, for several reasons. Firstly, because isolation is not cumulative. Sound and isolation work logarithmically, in both frequency and intensity, but mass only accumulates linearly. Meaning you cannot get high levels of isolation form a single-leaf wall, by just putting on lots and lots of layers of drywall. (Well, you can get there, but you need an impracticably huge number of layers).wondering if the multiple layering of drywall and green glue would have the cumulative effect I am looking for.
There's a principle of physics (and acoustics) called "Mass Law", which basically says that every time you double the mass on a wall, you get an increase of 5 dB in isolation. So starting with a single sheet of drywall, that gets you about 25 dB of isolation. Double that (total of two layers), and you get about 30 dB. Double that again (total of four layers) you get 35 dB. Double that again (total of 8 layers) and you get 40 dB. That's already one layer more than you planned to use, and you are only at a measly 40 dB! Not very heartening.
Here's the actual equation for empirical mass law, if you are interested:
TL = 14.5 log (Ms * 0.205) + 23 dB
Where: Ms = Surface Mass in kg/m2
Secondly, has to do with two of your other comments:
... and ...I am hoping to totally block sound from a 110 dB sound source from the other room that this wall is shared by.
That's actually impossible: There is no such thing as "100 % sound isolation". On this planet, any sufficiently loud sound will penetrate any conceivable barrier. The loudest ever sound on Earth (so far) was loud enough to crack concrete 300 miles away, and was heard around the globe. You can't stop sound. The very best isolated studio in the world is Galaxy Studios in Belgium: They get a little over 100 dB of isolation, and they achieved that by building each room as a hugely massive reinforced concrete bunker carefully isolated on enormous isolation springs with polymer rubber pads, inside another hugely massive concrete bunker. 100 dB of isolation is amazing, jaw-dropping even.... but still, if you fire a gun in one of those rooms it will be heard in the next room. Faintly, yes, but still audible. Because guns produce sounds at a level of about 150 dB upwards, so the sound from that would be heard at about 50 dB in the adjacent room (100 dB isolation: 150 -100 = 50).am more concerned with getting 100% sound isolation
So you cannot isolate 100%. It isn't possible. That's why we studio designers and acousticians don't like to use the word "soundproofing", because there's no such thing! We prefer "isolation".
But what you CAN do, is to isolate sounds down to a level where they are inaudible to the human ear. That, indeed, is achievable. For most people, if you place them in a location where the ambient sound level is 30 dBC, they will say that it is "silent". It isn't really silent, of course, since the level is 30 dB, which is 1000 times louder than the limit of human hearing, but most people consider that to be "silent" or at least "really, really, REALLY quiet".
So taking that as a reference, if you have a level of 110 dBC on one side of the wall, and you want subjective silence on the other side, then you need 110-30=80 dB of isolation.
80 dB of isolation is a tall, tall order. Very tall. Million dollar tall. It's beyond the capability of most home studios / project studios: It is achievable, but it is very high budget, and involves things like floated slabs and huge mass.
The practical isolation limit for most home studios is about 70 dB, as that's roughly the flanking limit for concrete slab on grade. That is do-able, but still hard. Most home studio builders are really happy to get 50 dB of isolation, and that's a reasonable goal to shoot for on a typical budget. 60 dB is also do-able, with good design and very careful construction.
So, with a 110 dB sound level on one side of the wall, 60 dB of isolation will get you about 50 dB on the other side of the wall. That is still audible, but certainly not loud at all.
There's also the spectrum to consider: If the sound you are isolating is strongest in the mid range, with not too much energy in the low end of the spectrum, then 60 dB of isolation will make it inaudible. For example, most power tools, vacuum cleaner, several people yelling and screaming at each other, etc. But if your 110 dB is a lone six-string bass guitar rehearsing all by itself at the level, it will be audible on the other side. Because isolation is not linear across the spectrum... isolating high frequencies is dead easy, mid range somewhat harder, and low frequencies, very hard.
That would make the isolation worse, not better...to build ... a "drywall wall" instead of using insulation to fill the cavities between studs.
I'm dead serious.
Above, I mentioned the concept of "mass law" above, since that's what you are talking about: making a single, solid wall that is purely mass. That's actually the worst type of wall you can have for isolation. Which is why studios NEVER use it.
The way to get good isolation (and the method used by all studios, including the 100 dB isolated Galaxy Studios) is with something called "fully decoupled two-leaf MSM isolation". This is also often called "room inside a room" construction. The basic concept is that you start with an empty piece of land, you pour a normal concrete slab on grade, then you build an outer "shell" building that has a decent amount of mass on it (but not hugely spectacular) concentrated in just one "leaf", then you build another structure inside that one, completely independent and self-supporting, such that it does not touch the outer building at all, and you also put one single leaf of mass on that.
For example: the outer building could be a stud frame with OSB and siding, plus an OSB roof deck with shingles, and all of that attached to the outside of the framing. So when you stand inside, you see studs and joists all around you, and the concrete floor. Then the inner-leaf building could also be a stud frame with drywall on only one side of it: just four walls and a ceiling, all framed and sheathed on just one side.
That's it! That's all you need.
The reason this works is because it is NOT subject to mass law! It is a resonant system, that is carefully tuned. Because it is resonant, it is subject to an entirely different set of equations that are only distantly related to mass law.
Resonance is a powerful tool. If you design the wall system correctly (tuned right), then you can get really good isolation like this, with not too much mass.
I could go into all the technical details of why this works, if you want, but suffice it to say that it does work, and it works very well. Much, much better than mass law. That's how I design all of my studios, and how pretty much all studio designers do it.
So you might think "Well, if one leaf is bad, and two leaves is good, then three leaves must be better!" And you'd be wrong...! 3-leaf, 4-leaf and multi-leaf systems actually turn out to have worse isolation in low frequencies, for complex technical reasons. The most efficient, most effective, lowest-cost method for isolating a studio, is fully-decouled, 2-leaf, MSM.
MLV has very few uses in acoustics. There are some places that it makes sense, but not as part of a sandwich of materials to build a wall. Despite what some manufactures try to tell you!I know about double stud frame wall construction techniques, MLV,
The truth is simple: the equations for isolation have no place for plugging in the price!
They have a place where you can plug in the mass (weight) of the material, and MLV certainly has mass. But so do many other things, such as drywall, fiber-cement board, brick, concrete block, MDF, OSB, plywood, etc. If you compare the cost-per-pound (or cost per kg), you'll find that MLV is dam expensive! It is mass, yes, but it is darn costly mass! Ans since sound waves don't know how to read price tags, they really don't care how much you paid for your mass. They just see the actual physical mass, and that's what they react to. so it makes sense to get the cheapest mass available that will do the job. In most places around the world, that is usually plain old drywall.Then do it the way we do it for pro mastering studios: fully-decoupled 2-laf MSM isolation, with the correct amount of mass on each leaf, and the correct air gap, and the correct damping material, such that your wall is tuned correctly for your needs, and provides the level of isolation that you need.I am trying to get the most bang for my buck here obviously, but am more concerned with getting 100% sound isolation for my own recording and mastering purposes.
The reason why you can't find any info on doing it the way you mentioned, is because it won't work! the laws of physics predict failure, so anybody who uses those equations will quickly figure out that it won't work, and would not try it. You are probably right: If anybody did try it (due to lack of understanding the laws of physics), then they would, indeed "fail miserably and never dare admit their mistake"! Very true.Either someone has tried this and has failed so miserably they would never dare admit their mistake and misfortune in public, or have been so successful in totally blocking massive SPL's that they have trademarked the idea and are profiteering it all the way around the world. Care to enlighten me?
I would suggest that you should take some time to study the acoustics and physics principles of sound isolation, and also to study the science/art of studio design, and the construction methods, techniques and common practices, so that you can correctly design your wall to be suitably tuned for the purpose.
It's not just wall design that you need to be concerned about: you can have a fantastic wall, ceiling and floor system that gets you amazing isolation, but then you have to put a door in it... doors are major weak points, since they have to open. You need to pay a lot of attention to your door design. Windows are weak point too, but the weakest point of all is usually the HVAC system. In order to stay alive in inside your studio, you need to breathe! (duh!). which implies that you need a constant supply of fresh air, and a way to exhaust the stale air. That implies shopping huge gaping holes in your perfect isolation, to pass the HVAC ducts through. There are ways of dealing with that, using specially designed "silencer boxes" that allow air to get through while stopping sound, but they have to be designed carefully too. In fact, the entire HVAC system has to be designed carefully, for many reasons: For example, moving air is noisy! The faster it moves, the noisier it is. So you have to design the entire system such that it moves enough air volume to keep you alive and comfortable while keeping the air flow speed down low enough that it does not make any noise that would interfere with your work or concentration. If you are mastering, you don't want a constant background "hiss" or "roar" coming from the HVAC vents!
Sound isolation is a huge subject. Since you are basically just starting out, realistically it will take you several months to get to the point where you can actually design the studio, then another couple of months of actual design work until you have the final complete design in hand. THEN you can think about construction. A well-regarded acoustician once said: "Building a studio is 90% design, 10% construction". When I first saw that, many many years ago, I thought he was kidding, or just trying to emphasize the important of design metaphorically. Now I realize that he was dead right, literally. The more time you spend in the design phase, getting every aspect perfect, the faster (and cheaper, and better) the building process will be.I am researching soundproofing and will begin a construction phase soon.
Don't rush!
- Stuart -
-
RAD
- Posts: 9
- Joined: Wed Sep 28, 2016 1:28 pm
- Location: San Jose Calif
Re: Drywall as insulation.
Yowza, Consider me enlightened.
So many details....I am basically going to modify a rehearsal studio to recording capability.
So thanks for answering my question, this is an extensive subject.
Basically I need to isolate sound coming into my room from two walls and a ceiling in my studio.
The sound sources are other bands in immediate and nearby proximity.
My current design method is this: per wall: Attaching a cut to fit layer of 5/8" drywall with staggered seams and green glue to an existing layer of 1/2" drywall on the inside of the next room, adding a layer of R13 UT 3.5" to bring it flush with the stud width, a Furring channel/clip Resilient channel system {Isotrax}
extending and decoupling the leaf by 1 1/2".
Finishing with 3 or 4 more layers of 5/8" drywall with green glue between each layer.
A layer of of 2lb MASS LOADED VINYL has been recommended to be the first layer attached to the furring channel. I think adding another layer of 5/8" drywall would accomplish the same effect.
Current wall construction is metal studs 24" O.C.
I plan on adding cross members of same metal studs across each wall assembly to stiffen it up to reduce vibration. I think I'm on the right track now...
Thanks again, amazing place.
RAD
So many details....I am basically going to modify a rehearsal studio to recording capability.
So thanks for answering my question, this is an extensive subject.
Basically I need to isolate sound coming into my room from two walls and a ceiling in my studio.
The sound sources are other bands in immediate and nearby proximity.
My current design method is this: per wall: Attaching a cut to fit layer of 5/8" drywall with staggered seams and green glue to an existing layer of 1/2" drywall on the inside of the next room, adding a layer of R13 UT 3.5" to bring it flush with the stud width, a Furring channel/clip Resilient channel system {Isotrax}
extending and decoupling the leaf by 1 1/2".
Finishing with 3 or 4 more layers of 5/8" drywall with green glue between each layer.
A layer of of 2lb MASS LOADED VINYL has been recommended to be the first layer attached to the furring channel. I think adding another layer of 5/8" drywall would accomplish the same effect.
Current wall construction is metal studs 24" O.C.
I plan on adding cross members of same metal studs across each wall assembly to stiffen it up to reduce vibration. I think I'm on the right track now...
Thanks again, amazing place.
RAD